/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package com.sun.org.apache.xml.internal.security.keys.content.x509;

import java.security.cert.X509Certificate;
import java.util.Arrays;

import com.sun.org.apache.xml.internal.security.exceptions.XMLSecurityException;
import com.sun.org.apache.xml.internal.security.utils.Base64;
import com.sun.org.apache.xml.internal.security.utils.Constants;
import com.sun.org.apache.xml.internal.security.utils.SignatureElementProxy;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

/**
 * Handles SubjectKeyIdentifier (SKI) for X.509v3.
 *
 * @see <A HREF="https://docs.oracle.com/javase/1.5.0/docs/api/java/security/cert/X509Extension.html">
 * Interface X509Extension</A>
 */
public class XMLX509SKI extends SignatureElementProxy implements XMLX509DataContent {

  /**
   * {@link org.apache.commons.logging} logging facility
   */
  private static java.util.logging.Logger log =
      java.util.logging.Logger.getLogger(XMLX509SKI.class.getName());

  /**
   * <CODE>SubjectKeyIdentifier (id-ce-subjectKeyIdentifier) (2.5.29.14)</CODE>:
   * This extension identifies the public key being certified. It enables
   * distinct keys used by the same subject to be differentiated
   * (e.g., as key updating occurs).
   * <BR />
   * A key identifier shall be unique with respect to all key identifiers
   * for the subject with which it is used. This extension is always non-critical.
   */
  public static final String SKI_OID = "2.5.29.14";

  /**
   * Constructor X509SKI
   */
  public XMLX509SKI(Document doc, byte[] skiBytes) {
    super(doc);
    this.addBase64Text(skiBytes);
  }

  /**
   * Constructor XMLX509SKI
   */
  public XMLX509SKI(Document doc, X509Certificate x509certificate)
      throws XMLSecurityException {
    super(doc);
    this.addBase64Text(XMLX509SKI.getSKIBytesFromCert(x509certificate));
  }

  /**
   * Constructor XMLX509SKI
   */
  public XMLX509SKI(Element element, String BaseURI) throws XMLSecurityException {
    super(element, BaseURI);
  }

  /**
   * Method getSKIBytes
   *
   * @return the skibytes
   */
  public byte[] getSKIBytes() throws XMLSecurityException {
    return this.getBytesFromTextChild();
  }

  /**
   * Method getSKIBytesFromCert
   *
   * @return ski bytes from the given certificate
   * @see java.security.cert.X509Extension#getExtensionValue(java.lang.String)
   */
  public static byte[] getSKIBytesFromCert(X509Certificate cert)
      throws XMLSecurityException {

    if (cert.getVersion() < 3) {
      Object exArgs[] = {Integer.valueOf(cert.getVersion())};
      throw new XMLSecurityException("certificate.noSki.lowVersion", exArgs);
    }

        /*
         * Gets the DER-encoded OCTET string for the extension value
         * (extnValue) identified by the passed-in oid String. The oid
         * string is represented by a set of positive whole numbers
         * separated by periods.
         */
    byte[] extensionValue = cert.getExtensionValue(XMLX509SKI.SKI_OID);
    if (extensionValue == null) {
      throw new XMLSecurityException("certificate.noSki.null");
    }

    /**
     * Strip away first four bytes from the extensionValue
     * The first two bytes are the tag and length of the extensionValue
     * OCTET STRING, and the next two bytes are the tag and length of
     * the ski OCTET STRING.
     */
    byte skidValue[] = new byte[extensionValue.length - 4];

    System.arraycopy(extensionValue, 4, skidValue, 0, skidValue.length);

    if (log.isLoggable(java.util.logging.Level.FINE)) {
      log.log(java.util.logging.Level.FINE, "Base64 of SKI is " + Base64.encode(skidValue));
    }

    return skidValue;
  }

  /**
   * @inheritDoc
   */
  public boolean equals(Object obj) {
    if (!(obj instanceof XMLX509SKI)) {
      return false;
    }

    XMLX509SKI other = (XMLX509SKI) obj;

    try {
      return Arrays.equals(other.getSKIBytes(), this.getSKIBytes());
    } catch (XMLSecurityException ex) {
      return false;
    }
  }

  public int hashCode() {
    int result = 17;
    try {
      byte[] bytes = getSKIBytes();
      for (int i = 0; i < bytes.length; i++) {
        result = 31 * result + bytes[i];
      }
    } catch (XMLSecurityException e) {
      if (log.isLoggable(java.util.logging.Level.FINE)) {
        log.log(java.util.logging.Level.FINE, e.getMessage(), e);
      }
    }
    return result;

  }

  /**
   * @inheritDoc
   */
  public String getBaseLocalName() {
    return Constants._TAG_X509SKI;
  }
}
